1. Field of the Invention
The present invention generally relates to an algorithm and method to modify the feeder movement of a sewing machine. More particularly, the present invention relates to an algorithm and method to modify the feeder movement of a sewing machine based on calibration data to achieve a desired stitch over the configuration and operating range of the machine.
2. Description of the Related Art
A modern sewing machine is able to produce a variety of stitches and seams on demand. During normal operation, the feeding of the fabric into the machine is controlled by a feed dog which is driven by a mechanism. The fabric is moved beneath the sewing needle by the movement of the feed dog.
The sewing machine includes a selection of stitches and seams. A seam is an entity composed of a number of stitches. Advanced sewing machines provide tools for creating new stitch elements by combining existing stitches, or seams. Data for each individual stitch, or seam can be reproduced as a graphic representation on a display, which may be integrated with the sewing machine.
The sewing machine is provided with a processor, a control program, and a memory. The control program may be integral with the processor or stored in memory. The memory is accessible by the processor and may either be accommodated within the machine or may be external. Data for each individual stitch, or seam, is stored in a database within the memory. A display may be provided upon which the graphic elements representing the stitch, or seams, may be displayed to the user.
The user wishes the actual seam that is sewn upon the fabric to look like the stitches selected. During a sewing operation, the fabric is moved across the stitch plate and beneath the reciprocating needle by a feed dog. The feeding of the fabric beneath the sewing needle is critical to achieve the intended stitch size and shape. The feed dog is driven by a feeding mechanism which is synchronized with the needle movement. Many factors effect the actual movement of the fabric relative to the movement of the feed dog. Feeding errors commonly occur in the form of slippage or uneven movement between the feed dog and fabric. The type and magnitude of feeding error is dependent upon many factors. The end result of all feeding errors in passing the fabric beneath the needle results in stitches or seams that are misshapen, or of improper size, and that are not what the user intended.
Due to the problems above in the feeding of fabric to achieve an expected and consistent seam, it would be advantageous to provide an algorithm and method to predict and compensate for feeding errors. Such an algorithm and method would provide for modified feeder movement to achieve the required fabric positioning during the sewing operation. The algorithm and method would insure a consistent stitch size over a variety of fabrics, threads, and operating conditions. It is thus to such a feeder movement compensation algorithm and method that the present invention is primarily directed.